A Method for Studying the External Anatomy of Copepods
TL;DR: In this article, it was shown that lactic acid is the best clearing agent for the preparation of temporary mounts of whole or dissected copepods, and that obese forms or specimens with a thin cuticle are best transferred through mixtures of the medium in which they have been kept and Lactic acid.
Abstract: We have found lactic acid to be the best clearing agent for the preparation of temporary mounts of whole or dissected copepods. Fresh, alcoholic, or formalin fixed specimens become cleared within a few minutes to some hours, depending upon their size and the duration of preservation. When first placed in the un diluted acid, the copepods may become somewhat contracted, but soon regain, and thereafter retain, their normal size and shape. In order to avoid rupture, obese forms or specimens with a thin cuticle are best transferred through mixtures of the medium in which they have been kept and lactic acid. Since the latter is dense, layering the fluids in a small dish is usually satisfactory: the original medium will evaporate slowly, leaving the speci mens in the acid. Fluids with appreciable concentrations of dissolved salts, however, should be avoided, preferably by transferring the specimens first either to alcohol or to fresh-water.
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TL;DR: The life cycle of C. elongatus, known as a sea louse, is a very important pathogen of sea-farmed Atlantic salmon (Salmo salar) and was examined under laboratory conditions.
Abstract: Caligus elongatus, known as a sea louse, is a very important pathogen of sea-farmed Atlantic salmon (Salmo salar). The life cycle of C. elongatus was examined under laboratory conditions. The obser...
56 citations
TL;DR: Larvae of Alpheus heterochaelis from North Carolina hatch from large eggs as advanced zoeae, usually moult three times, and exhibit almost no linear growth during a short (4 days at 25°c) larval development.
Abstract: Summary Larvae of Alpheus heterochaelis from North Carolina hatch from large eggs as advanced zoeae, usually moult three times, and exhibit almost no linear growth during a short (4 days at 25°c) larval development. Stage I lasts 6 hours at most and is sometimes skipped; III lasts about twice as long as II. Individuals simultaneously exhibiting characteristics of Stage III and the postlarva were occasionally seen. The three zoeal stages and postlarva are described in detail and illustrated. Stages in embryonic and juvenile development and the hatching process are briefly described. An ‘extended’ pattern of larval development, characteristic of most alpheid species, is described in a general way, and the ‘abbreviated’ development of A. heterochaelis compared to it. At hatching, A. heterochaelis larvae bear rudimentary pereiopods and pleopods; other structures are at the same level of development in both patterns, but subsequent morphogenesis is faster in A. heterochaelis. Larval development of Synalpheus s...
53 citations
TL;DR: The results suggest that conservation of the biodiversity and numbers of aquatic predators may limit adverse impacts of trematode infections in vertebrate hosts and suggest the need for field and laboratory studies to further explore the effects of predators on transmission of R. ondatrae to amphibian larvae.
Abstract: Trematodes amplify asexually in their snail intermediate hosts, resulting in the potential release of hundreds to thousands of free-living cercariae per day for the life of the snail. The high number of cercariae released into the environment undoubtedly increases the probability of transmission. Although many individual cercariae successfully infect another host in their life cycle, most fail. Factors that prevent successful transmission of cercariae are poorly understood. Microcrustaceans and fish have been observed to eat cercariae of some species, although the possibility that predation represents a significant source of mortality for cercariae has been largely unexplored. We tested the cercariophagic activity of several freshwater invertebrates on Ribeiroia ondatrae, a trematode that causes limb deformities in amphibians. Individuals of potential predators were placed into wells of multiwell plates with 10–15 cercariae, and numbers of cercariae remaining over time were recorded and compared with numb...
51 citations
Cites background from "A Method for Studying the External ..."
...Later, copepods were cleared in 90% lactic acid (Humes and Gooding, 1964)....
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TL;DR: The morphology of all developmental stages of the fish parasite Caligus elongatus (Copepoda; Caligidae) is described in this article, where the entire life cycle consists of 8 stages: 2 nauplii, 1 copepodid, 4 chalimi, and adults.
Abstract: The morphology of all developmental stages of the fish parasite Caligus elongatus (Copepoda; Caligidae) is described. The entire life cycle consists of 8 stages: 2 nauplii, 1 copepodid, 4 chalimi, and adults. A preadult stage does not occur as it does in some other caligids. In this respect C. elongatus differs substantially from the other major sea louse species, Lepeophtheirus salmonis, which has two preadult stages.
48 citations
TL;DR: A wide range of aspects concerning microscope slides, their preparation, long-time storage, curatorial measures in collections, deterioration, restoration, and study is summarized based on more than 600 references from the 19 th century until 2016, 15 patents, and about 100 Materials Safety Data Sheets.
Abstract: A wide range of aspects concerning microscope slides, their preparation, long-time storage, curatorial measures in collections, deterioration, restoration, and study is summarized based on our own data and by analyzing more than 600 references from the 19 th century until 2016, 15 patents, and about 100 Materials Safety Data Sheets. Information from systematic zoology, conservation sciences, chemistry, forensic sciences, pathology, paleopathology, applied sciences like food industry, and most recent advances in digital imaging are put together in order to obtain a better understanding of which and possibly why mounting media and coverslip seals deteriorate, how slides can be salvaged, which studies may be necessary to identify a range of ideal mounting media, and how microscope studies can benefit from improvements in developmental biology and related fields. We also elaborate on confusing usage of concepts like that of maceration and of clearing. The chemical ingredients of a range of mounting media and coverslip seals are identified as much as possible from published data, but this information suffers in so far as the composition of a medium is often proprietary of the manufacturer and may vary over time. Advantages, disadvantages, and signs of deterioration are documented extensively for these media both from references and from our own observations. It turns out that many media degrade within a few years, or decades at the latest, except Canada balsam with a documented life-time of 150 years, Euparal with a documented life-time of 50 years, and glycerol-paraffin mounts sealed with Glyceel, which represents almost the only non-deteriorating and easily reversible mount. Deterioration reveals itself as a yellowing in natural resins and as cracking, crystallization, shrinkage on drying or possibly on loss of a plasticizer, detachment of the coverslip, segregation of the ingredients in synthetic polymers, as well as continued maceration of a specimen to a degree that the specimen virtually disappears. Confusingly, decay does not always appear equally within a collection of slides mounted at the same time in the same medium. The reasons for the deteriorative processes have been discussed but are controversial especially for gum-chloral media. Comparing data from conservation sciences, chemical handbooks, and documented ingredients, we discuss here how far chemical and physical deterioration probably are inherent to many media and are caused by the chemical and physical properties of their components and by chemicals dragged along from previous preparation steps like fixation, chemical maceration, and physical clearing. Some recipes even contain a macerating agent, which proceeds with its destructive work. We provide permeability data for oxygen and water vapor of several polymers contained in mounting media and coverslip seals. Calculation of the penetration rate of moisture in one example reveals that water molecules reach a specimen within a few days up to about a month; this lays to rest extensive discussions about the permanent protection of a mounted specimen by a mounting medium and a coverslip seal. Based on the ever growing evidence of the unsuitable composition and application of many, and possibly almost all, mounting media, we strongly encourage changing the perspective on microscope slides from immediate usability and convenience of preparation towards durability and reversibility, concepts taken from conservation sciences. Such a change has already been suggested by Upton (1993) more than 20 years ago for gum-chloral media, but these media are still encouraged nowadays by scientists. Without a new perspective, taxonomic biology will certainly lose a large amount of its specimen basis for its research within the next few decades. Modern non-invasive techniques like Raman spectroscopy may help to identify mounting media and coverslip seals on a given slide as well as to understand ageing of the media. An outlook is given on potential future studies. In order to improve the situation of existing collections of microscope slides, we transfer concepts as per the Smithsonian Collections Standards and Profiling System, developed for insect collections more than 25 years ago, to collections of slides. We describe historical and current properties and usage of glass slides, coverslips, labels, and adhesives under conservational aspects. In addition, we summarize and argue from published and our own experimental information about restorative procedures, including re-hydration of dried-up specimens previously mounted in a fluid medium. Alternatives to microscope slides are considered. We also extract practical suggestions from the literature concerning microscope equipment, cleaning of optical surfaces, health risks of immersion oil, and recent improvements of temporary observation media especially in connection with new developments in digital software.
43 citations
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7 citations
"A Method for Studying the External ..." refers methods in this paper
...A useful modification for the dissecting microscope is the device suggested by Harding (1939), which permits focusing by the move ment of one knee, thus completely freeing both hands....
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TL;DR: An investigation of the microfauna of the shore at Whitstable, Kent, it was necessary to examine and to identify the many Harpacticoid copepods which occurred there.
Abstract: DURING an investigation of the microfauna of the shore at Whitstable, Kent, it was necessary to examine and to identify the many Harpacticoid copepods which occurred there. At the same time it was desirable to build up a type collection of these animals.
6 citations